Method for producing a blind hole in a metallic body

Abstract

The invention relates to a method for producing a blind hole (10) in a metallic workpiece having at least one curved surface. One part of the material is pushed starting from approximately the horizontally extending curved tangent and from there approximately perpendicular in the direction of the material of the workpiece by means of reciprocating movement. Said method consists of the following steps: a) providing the workpiece with a matrix-type receiving element (16) for the material which is to be displaced; b) pushing the workpiece material by means of a stamp in the axial direction of the receiving element (16), said material stamped by the stamp is initially sheared in an adiabatic state and flows partially into the receiving element (16); c) removing (16) the material projecting from the receiving element.

Description

The invention concerns, as an alternative to drilling, a method for producing a blind hole in a metallic workpiece comprising at least one curved surface, wherein machining is done beginning approximately at the horizontal tangent and approximately transverse thereto in the direction of the material of the workpiece.

In conventionally drilled blind holes cuttings are produced inevitably. Moreover, such bores can be introduced only at a limited speed.

Increasing the drilling speed is not possible with conventional means. Also, it must be considered that the workpieces must be cleaned and deburred, which requires additional time.

Up to now, no evidence has been found that a blind hole can be produced without a drill.

The invention has therefore the object to develop a method that enables providing metallic bodies with blind holes with high precision and also with a significantly increased speed.

This object is solved by the following method:

Method for producing a blind hole in a metallic workpiece comprising at least one curved surface, wherein, beginning approximately at the horizontally extending curvature tangent and approximately transverse thereto in the direction of the material of the workpiece, by means of a stroke movement a part of the material is displaced, comprising the steps:

• • a) providing the workpiece with a die-shaped receptacle for the material to be displaced;
  • b) displacing the material of the workpiece by means of a plunger (18) in axial direction of the receptacle, wherein the material that is impacted by the plunger (18) is initially cut in an adiabatic state and partially flows into the receptacle; and
  • c) removal of the material projecting into the receptacle.

The gist of the invention resides in transferring the corresponding material locations in the metallic body into an adiabatic state in order to avoid plastic deformations at the impact area. For this purpose, no drill is required that wears quickly. Moreover, in this context, no cuttings are produced that may cause processing disturbances.

A further embodiment of the invention provides that the diameter of the receptacle is smaller than the diameter of the plunger.

This enables a precise adjustment of the depth and width of the blind hole because due to the smaller diameter of the receptacle the material can be driven out in the correct ratio so that still sufficient material for formation of the blind hole bottom is remaining. Also, the protrusion of the plunger relative to the receptacle provides an annular area that cannot be displaced too quickly so that this annular area ensures that a bottom area remains after the stamping or stroke process.

Preferably, it is provided that the receptacle for the displaced material is arranged above the workpiece.

Moreover, it has been found to be advantageous when the impact speed is <10 m/s, preferably 6 m/s up to 8 m/s, which is sufficient for producing the adiabatic state.

Particularly advantageously, the impact speed is 7 m/s.

This is in contrast to the disclosure of the publication DE 103 17 185 where it is disclosed that the adiabatic state is generated only at a stroke speed of more than 10 m/s.

It is particularly advantageous when the cross-section of the metallic workpiece is of a triangular or semi-circular shape, has at least one rounded corner, and the blind bore extends beginning at the highest point of the curvature transversely to the line that is connecting the two remaining corners.

A further embodiment of the invention provides that the workpiece is supplied as elongate material with desired cross-section to the processing station for producing the blind hole and is then adiabatically cut to length to the final size, or is adiabatically individualized to the final size already beforehand and supplied to the processing station.

It has been found to be particularly advantageous when this method is used for producing sliding blocks.

In this context, it is advantageous when this sliding block is also provided with a through hole by using the method for producing through hole through holes according to the simultaneously filed and pending patent application “Method for producing a through hole in a metallic body”, filed on Feb. 5, 2013.

Finally, it can also be provided to first produce the through holes and then the blind holes.

Further advantages and features of the invention result from the following description of an embodiment as well as from the drawings to which reference is being had. It is expressly noted that the description is based on manufacturing a sliding block but is in no way limited thereto. It is shown in:

FIG. 1 a cross-section of the initial situation which is viewed at the site marked with the large arrow transversely to the manufacturing line:

FIG. 2 shows a cross-section similar to FIG. 1 wherein however the plunger already has penetrated into the metallic body, in this case the sliding block;

FIG. 3 a view similar to FIG. 2, wherein however the plunger has been completely inserted into the metallic body and the pin received in the receptacle according to the drawing is to be sheared off to the right and can be removed through the blind hole; and

FIG. 4 a view similar to FIG. 3 wherein the receptacle contents has already been removed through the blind hole.

With the aid of FIGS. 1 to 4, the manufacture or the method for producing a blind hole 10 within, in this case, a metallic sliding block 12 that has a curved surface is disclosed. It is again noted that the description of the sliding block is only given as an example because the method according to the invention of course can also be applied to and used for other metallic bodies with curved surfaces.

FIG. 1 shows the initial position for an adiabatic displacement of a blind hole 10. The workpiece 12, which is of course a sliding block 12 in this case, is received in such a way in a holder 14 that the rounded portion of the cross-section that is in this case of a semi-circular shape is oriented downward. The workpiece 12 to be processed is secured on its topside by a receptacle 16 provided with a cutout or a cavity for the material to be displaced in alignment with a plunger 18.

The sliding block 12 or the section not yet machined is thus secured from above and from below.

From the schematically illustrated sequence of manufacturing steps in all FIGS. 1 to 4 it can be seen that so-called through holes are produced beforehand and also are provided with a thread.

In all FIGS. 1 to 4, the large arrow always points in the direction of the section that is illustrated as a great cross-section.

Beginning with the position according to FIG. 1, by means of a plunger 18 the material of the workpiece is now displaced in axial direction of the receptacle 16, as illustrated in FIG. 2, wherein the material impacted by the plunger 18 is transferred into an adiabatic state and is partially displaced into the cavity 16 provided therefore.

Subsequently, according to FIG. 3, the receptacle 16 can now be displaced freely to the right because the plunger 18 has already been pulled out of the blind hole 10.

The receptacle 16 according to FIG. 4 is moved to the right to such an extent that the sheared-off pin reaches the through hole Du and in this way can drop downwardly.

In order to prevent that upon stamping or displacement of the excess material into the receptacle 16 the material that is in the adiabatic state is pushed through the surface of the sliding block 12 so that a hole is produced, the diameter d in the receptacle 16 is smaller than the diameter of the plunger 18. Therefore, essentially a small ring is formed in the area of the sliding block 12 which is essentially retained by the smaller diameter d of the opening of the receptacle 16. The receptacle 16 therefore secures an annular part of the future bottom of the blind hole 10 of the sliding block 12.

It is of course also possible to arrange the arrangement in reverse compared to FIGS. 1 to 4. However, it has been found to be advantageous when the receptacle 16 for the displaced material is arranged above the workpiece 12.

Even though, as already explained in the introduction, the publication DE 103 17 185 A1 expressly states that an adiabatic state occurs only at speeds of more than 10 m/s, it has been found for the illustrated arrangement that also lower speeds of, for example, 6 m/s to 8 m/s and preferably 7 m/s can be employed in order to obtain an adiabatic state for the punching process.

In contrast to the semi-circular workpieces 12 illustrated in FIGS. 1 to 4 it is however also possible that the cross-section of the metallic workpiece 12 is triangular wherein at least one rounded corner is existing which can be used for entry of the plunger or stamp 18 for generating the blind hole 10.

FIGS. 1 to 4 show also that the manufacture of the metallic workpieces 12, in this case the sliding blocks 12, as a starting material a long wire with the aforementioned cross-sections can be used in order to be able to employ an assembly line-type processing. It is however also possible to cut to length beforehand the defined workpieces 12 and then supply them in appropriate rails, like on an assembly line, to the individual processing stations.

By means of the invention it is now made possible to produce blind holes that have a flat bottom and no longer the conical depressions which are produced upon drilling. In particular in case of the sliding blocks, this has the advantage that the springs that are inserted into the blind holes for supporting a ball are always seated with precise fit and cannot move; of course, with the exception of the spring travel. In order to secure the balls placed onto the springs within the blind hole, the outer walls of the blind hole are swedged.

LIST OF REFERENCE NUMBERS

10 blind hole

12 workpiece

14 holder

16 receptacle

18 plunger

D diameter

Claims

1.-10. (canceled)

11. A method for producing a blind hole in a metallic workpiece having at least one curved surface, comprising the steps: a) placing the workpiece into a receptacle comprising a cavity;b) displacing a portion of the material of the metallic workpiece partially into the cavity of the receptacle, beginning at a horizontal curvature tangent of the at least one curved surface and approximately transverse to the curvature tangent in the direction of the material of the metallic workpiece, by impacting the material of the metallic workpiece with a plunger in an axial direction of the cavity of the receptacle by a stroke movement and shearing off in an adiabatic state the portion of the material that is impacted by the plunger; andc) removing the material which is projecting into the cavity of the receptacle.

12. The method according to claim 11, further comprising selecting a diameter (d) of the cavity of the receptacle (16) to be smaller than a diameter (D) of the plunger (18).

13. The method according to claim 11, further comprising positioning the receptacle above the metallic workpiece.

14. The method according to claim 11, further comprising impacting the plunger at an impact speed of 6 m/s to 8 m/s for reaching the adiabatic state.

15. The method according to claim 14, wherein the impact speed is 7 m/s.

16. The method according to claim 11, further comprising selecting a cross-section of the metallic workpiece to be of a triangular or semi-circular shape comprising at least one rounded corner, wherein the blind hole extends, beginning at a highest point of the curvature of the at least one rounded corner, transversely to a line connecting the two remaining corners of the triangular or semi-circular shape.

17. The method according to claim 11, further comprising supplying elongate material with a desired cross-section to a processing station for producing the blind hole and adiabatically cutting to length the elongate material to a final size of the metallic workpiece.

18. The method according to claim 11, further comprising adiabatically individualizing from an elongate material with a desired cross-section the metallic workpiece of a final size and subsequently supplying the metallic workpiece to a processing station for producing the blind hole.

19. The method according to claim 11, wherein the metallic workpiece is a sliding block.

20. The method according to claim 19, further comprising the step of producing a through hole in the sliding block.

21. The method according to claim 20, wherein first the through hole and then the blind hole is produced in the sliding block.

22. The method according to claim 20, wherein first the blind hole and then the through hole is produced in the sliding block.